Ferroresonant Transformers

Thanks to the electromagnetic phenomenon known as ferroresonance, these transformers are also known as Constant-Voltage Transformers (CVT). A CVT regulates its secondary voltage typically within a few percent even when the primary voltage changes as much as 15-20 percent. Accompanying these transformers is a bank of capacitors. These capacitors are used to tune the output voltage of the CVT and are essential to its proper operation.